Study on the characteristics of soil carbon accumulation and conversion of carbon sink and source of grassland under different land use types

Landuse change is the main affecting factor of soil carbon storage. It is very important to predict the trend of soil carbon release under different landuse patterns so that the soil carbon accumulation and conversion of soil carbon sink and source could be better understand. The organic carbon density and variation patterns of organic carbon storage within 0 to 30 cm soil layer of fenced grassland and grazing land in the southeast of Horqin sandy land were studied from May to November. The results showed that the soil organic carbon content of enclosed grassland decreased significantly with the soil depth, but not for the grazing land. Soil organic carbon density of the fenced grassland within 0 to 30 cm soil layer varied from 2.8 kg/m2 to 4.0 kg/m2. And it was from 3.4 kg/m2 to 4.7 kg/m2 for the grazing land. In general, it was the carbon source process from May to August and from September to November, and it was the carbon sink process from August to September for the fenced land. However, soil carbon storage of the grazing land was more stable, the conversion process of soil carbon sink and source was no significant. It suggested that the reasonable grazing utilization contributed to accumulation of soil carbon and could reduce carbon emission.